1. Field of Invention
The present invention relates to monitoring of water quality and, more particularly, to a level-tracing water-monitoring apparatus.
2. Prior Art
While developing, the world is encountering a serious problem of pollution. Water pollution could be the worst among all types of pollution. A lot of pollutants are dumped to reservoirs and open channels from fixed sources such as factories and farms, or from mobile sources such as vehicles. In some cases, such pollutants are directly released into water. In some other cases, such pollutants are disposed of on the ground and then washed into the water by rain. Once introduced into the water, such pollutants inevitably increase costs in treating the water and very often harm human bodies, life stock and aquatic lives.
Before any proper measure can be taken to solve the problem of water pollution, by what pollutants and to what extent the water is polluted must be analyzed. In other words, various quality parameters of the water must be detected.
In early days, prior to analyses, water was manually sampled. Manual sampling has always been expensive and cumbersome. Therefore, manual sampling was conducted on an irregular basis and rarely.
To achieve regular and frequent sampling, it must be done automatically. There have been installed some conventional monitoring stations into which water is automatically pumped through pipes. It is, however, found difficult to have the pipes catch up with the water level changing vigorously from season to season. When the water level becomes too low for the pipes to reach, it is impossible to pump water through the pipes.
To continuously monitor the water, some water-monitoring apparatuses have been devised with sensors are carried by means of a buoy tied to a bank or a well by means of a cable. To have the buoy float on the water when the water level is low, a sufficiently long cable is used. However, the cable allows the buoy to drift for a long distance in any direction when the water level is high. As the buoy drifts, the cable often tangles with miscellaneous objects, e.g., twigs. This could seriously affect the operation of the sensors.
To prevent the cable from tangling with miscellaneous objects, there has been devised a length control device in which the cable is wound on a reel operatively connected with a motor. The motor can be activated to rotate the reel to adjust a length of the cable extending from the reel so that the sensors can always be immerged in water. However, the motor consumes a lot of energy.
In addition, to transmit signals from the sensors to a monitoring station, the cable is connected to the monitoring station through a signal relay including a mandrel electrically connected with the cable. The mandrel rotates together with the reel. The signal relay further includes a brush electrically connected with the monitoring station. The brush does not rotate. The mandrel is in rotational engagement with the brush, thus allowing the mandrel to rotate with respect to the brush while allowing the signals to be transmitted from the mandrel to the brush. However, friction between the mandrel and the brush interferes with the rotation of the reel and wears out the brush after serving for a period of time.
In a co-pending patent application, the inventor teaches a water-monitoring apparatus including a length control device and a non-contact relay. The length control device includes a reel on which a cable is wound. A buoy is connected with the cable. A sensor is used to detect a water quality parameter and to produce a signal representative of the water quality parameter. The sensor is carried by means of the buoy and electrically connected with the cable. The reel can be rotated to adjust a length of the cable extending from the reel so that the sensor can always be immersed in the water. The non-contact relay includes a transmitter and a receiver. The transmitter is electrically connected with the cable and rotated together with the reel. The receiver is installed in a proper position by the water. The transmitter and the receiver are in non-contact communication of signal with each other. Such a water-monitoring apparatus is excellent in performance; however, it is expensive due to the use of the cable and of the non-contact relay. The cable is made by enclosing an ordinary electric wire with a steel sheath to provide two functions: transmission of signal and strength against forces exerted thereon. Production of such a cable is expensive. The use of the transmitter and the receiver and related circuits costs a lot of money, too.
Therefore, the present invention is intended to alleviate or even obviate the drawbacks encountered in prior art.
It is the primary objective of the present invention to provide a water-monitoring apparatus capable of automatically tracing water level.
It is another objective of the present invention to provide a water-monitoring apparatus including a sensor, a buoy for carrying the sensor, a tension cable for tying the buoy to a position by the water and a signal wire for connecting the sensor with a monitor device wherein the tension cable and the signal wire are both free of tangle.
According to an aspect of the present invention, a water-monitoring apparatus includes a frame installed in a proper position by water. A reel is mounted on the frame. A constant force device is used to exert a constant force on the reel. A tension cable including a lower end and an upper end is wound on the reel. A buoy is connected with the tension cable. A detecting device is used for detecting at least one water quality parameter. The detecting device is carried by means of the buoy. The detecting device is connected with a monitor device through a signal wire. The signal wire includes a helical section extending around a lower section of the tension cable. The helical section enables the signal wire to automatically adjust a distance between its two ends according to the position of the buoy.